(* Title:  Test_Z_Transform

   Author: Jan Rocnik

   (c) copyright due to lincense terms.

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*)

theory Build_Inverse_Z_Transform imports 

  Isac "../../../../../../src/Tools/isac/Knowledge/Partial_Fractions"

begin

text{* We stepwise build Inverse_Z_Transform.thy as an exercise.

  Because subsection "Stepwise Check the Program" requires Inverse_Z_Transform.thy 

  as a subtheory of Isac.thy, the setup has been changed from

  "theory Inverse_Z_Transform imports Isac begin.." to the above.

  ATTENTION WITH NAMES OF IDENTIFIERS WHEN GOING INTO INTERNALS:

  Here in this theory there are the internal names twice, for instance we have

  (Thm.derivation_name @{thm rule1} = "Build_Inverse_Z_Transform.rule1") = true;

  but actually in us will be "Inverse_Z_Transform.rule1"

*}

ML {*val thy = @{theory Isac};*}

section {*trials towards Z transform *}

text{*===============================*}

subsection {*terms*}

ML {*

@{term "1 < || z ||"};

@{term "z / (z - 1)"};

@{term "-u -n - 1"};

@{term "-u [-n - 1]"}; (*[ ] denotes lists !!!*)

@{term "z /(z - 1) = -u [-n - 1]"};Isac

@{term "1 < || z || ==> z / (z - 1) = -u [-n - 1]"};

term2str @{term "1 < || z || ==> z / (z - 1) = -u [-n - 1]"};

*}

ML {*

(*alpha -->  "</alpha>" *)

@{term "\<alpha> "};

@{term "\<delta> "};

@{term "\<phi> "};

@{term "\<rho> "};

term2str @{term "\<rho> "};

*}

subsection {*rules*}

(*axiomatization "z / (z - 1) = -u [-n - 1]" Illegal variable name: "z / (z - 1) = -u [-n - 1]" *)

(*definition     "z / (z - 1) = -u [-n - 1]" Bad head of lhs: existing constant "op /"*)

axiomatization where 

  rule1: "1 = \<delta>[n]" and

  rule2: "|| z || > 1 ==> z / (z - 1) = u [n]" and

  rule3: "|| z || < 1 ==> z / (z - 1) = -u [-n - 1]" and 

  rule4: "|| z || > || \<alpha> || ==> z / (z - \<alpha>) = \<alpha>^^^n * u [n]" and

  rule5: "|| z || < || \<alpha> || ==> z / (z - \<alpha>) = -(\<alpha>^^^n) * u [-n - 1]" and

  rule6: "|| z || > 1 ==> z/(z - 1)^^^2 = n * u [n]"

ML {*

@{thm rule1};

@{thm rule2};

@{thm rule3};

@{thm rule4};

*}

subsection {*apply rules*}

ML {*

val inverse_Z = append_rls "inverse_Z" e_rls

  [ Thm  ("rule3",num_str @{thm rule3}),

    Thm  ("rule4",num_str @{thm rule4}),

    Thm  ("rule1",num_str @{thm rule1})   

  ];

val t = str2term "z / (z - 1) + z / (z - \<alpha>) + 1";

val SOME (t', asm) = rewrite_set_ thy true inverse_Z t;

term2str t' = "z / (z - ?\<delta> [?n]) + z / (z - \<alpha>) + ?\<delta> [?n]"; (*attention rule1 !!!*)

*}

ML {*

val (thy, ro, er) = (@{theory Isac}, tless_true, eval_rls);

*}

ML {*

val SOME (t, asm1) = rewrite_ thy ro er true (num_str @{thm rule3}) t;

term2str t = "- ?u [- ?n - 1] + z / (z - \<alpha>) + 1"; (*- real *)

term2str t;

*}

ML {*

val SOME (t, asm2) = rewrite_ thy ro er true (num_str @{thm rule4}) t;

term2str t = "- ?u [- ?n - 1] + \<alpha> ^^^ ?n * ?u [?n] + 1"; (*- real *)

term2str t;

*}

ML {*

val SOME (t, asm3) = rewrite_ thy ro er true (num_str @{thm rule1}) t;

term2str t = "- ?u [- ?n - 1] + \<alpha> ^^^ ?n * ?u [?n] + ?\<delta> [?n]"; (*- real *)

term2str t;

*}

ML {*

terms2str (asm1 @ asm2 @ asm3);

*}

section {*Prepare steps in CTP-based programming language*}

text{*===================================================*}

subsection {*prepare expression*}

ML {*

val ctxt = ProofContext.init_global @{theory Isac};

val ctxt = declare_constraints' [@{term "z::real"}] ctxt;

val SOME fun1 = parseNEW ctxt "X z = 3 / (z - 1/4 + -1/8 * z ^^^ -1)"; term2str fun1;

val SOME fun1' = parseNEW ctxt "X z = 3 / (z - 1/4 + -1/8 * (1/z))"; term2str fun1';

*}

axiomatization where

  ruleZY: "(X z = a / b) = (X' z = a / (z * b))"

ML {*

val (thy, ro, er) = (@{theory Isac}, tless_true, eval_rls);

val SOME (fun2, asm1) = rewrite_ thy ro er true  @{thm ruleZY} fun1; term2str fun2;

val SOME (fun2', asm1) = rewrite_ thy ro er true  @{thm ruleZY} fun1'; term2str fun2';

val SOME (fun3,_) = rewrite_set_ @{theory Isac} false norm_Rational fun2;

term2str fun3; (*fails on x^^^(-1) TODO*)

val SOME (fun3',_) = rewrite_set_ @{theory Isac} false norm_Rational fun2';

term2str fun3'; (*OK*)

*}

subsection {*build equation from given term*}

ML {*

val (_, expr) = HOLogic.dest_eq fun3'; term2str expr;

val (_, denom) = HOLogic.dest_bin "Rings.inverse_class.divide" (type_of expr) expr;

term2str denom = "-1 + -2 * z + 8 * z ^^^ 2";

*}

text {*we have rhs in the language, but we need a function 

  which gets the denominator of a fraction*}

ML {*

(*GOON ==========================================================================================*)

*}

ML {*

*}

ML {**}

subsection {*solve equation*}

text {*this type of equation if too general for the present program*}

ML {*

"----------- Minisubplb/100-init-rootp (*OK*)bl.sml ---------------------";

val denominator = parseNEW ctxt "z^^^2 - 1/4*z - 1/8 = 0";

val fmz = ["equality (z^^^2 - 1/4*z - 1/8 = (0::real))", "solveFor z","solutions L"];

val (dI',pI',mI') =("Isac", ["univariate","equation"], ["no_met"]);

(*                           ^^^^^^^^^^^^^^^^^^^^^^ TODO: ISAC determines type of eq*)

*}

text {*Does the Equation Match the Specification ?*}

ML {*

match_pbl fmz (get_pbt ["univariate","equation"]);

*}

ML {*Context.theory_name thy = "Isac"(*==================================================*)*}

ML {*

val denominator = parseNEW ctxt "-1/8 + -1/4*z + z^^^2 = 0";

val fmz =                                            (*specification*)

  ["equality (-1/8 + (-1/4)*z + z^^^2 = (0::real))", (*equality*)

   "solveFor z",                                     (*bound variable*)

   "solutions L"];                                   (*identifier for solution*)

(*liste der theoreme die zum lösen benötigt werden, aus isac, keine spezielle methode (no met)*)

val (dI',pI',mI') =

  ("Isac", ["pqFormula","degree_2","polynomial","univariate","equation"], ["no_met"]);

*}

text {*Does the Other Equation Match the Specification ?*}

ML {*

match_pbl fmz (get_pbt ["pqFormula","degree_2","polynomial","univariate","equation"]);

*}

text {*Solve Equation Stepwise*}

ML {*

val (p,_,f,nxt,_,pt) = CalcTreeTEST [(fmz, (dI',pI',mI'))];

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;

val (p,_,f,nxt,_,pt) = me nxt p [] pt;         

val (p,_,f,nxt,_,pt) = me nxt p [] pt; (*nxt =..,Check_elementwise "Assumptions")*)

val (p,_,f,nxt,_,pt) = me nxt p [] pt;         

val (p,_,f,nxt,_,pt) = me nxt p [] pt; f2str f;

(*[z = 1 / 8 + sqrt (9 / 16) / 2, z = 1 / 8 + -1 * sqrt (9 / 16) / 2] TODO sqrt*)

show_pt pt; 

val SOME f = parseNEW ctxt "[z=1/2, z=-1/4]";

*}

subsection {*partial fraction decomposition*}

subsubsection {*solution of the equation*}

ML {*

val SOME solutions = parseNEW ctxt "[z=1/2, z=-1/4]";

term2str solutions;

atomty solutions;

*}

subsubsection {*get solutions out of list*}

text {*in isac's CTP-based programming language: let$ $s_1 = NTH 1$ solutions; $s_2 = NTH 2...$*}

ML {*

val Const ("List.list.Cons", _) $ s_1 $ (Const ("List.list.Cons", _) $

      s_2 $ Const ("List.list.Nil", _)) = solutions;

term2str s_1;

term2str s_2;

*}

ML {* (*Solutions as Denominator --> Denominator1 = z - Zeropoint1, Denominator2 = z-Zeropoint2,...*)

val xx = HOLogic.dest_eq s_1;

val s_1' = HOLogic.mk_binop "Groups.minus_class.minus" xx;

val xx = HOLogic.dest_eq s_2;

val s_2' = HOLogic.mk_binop "Groups.minus_class.minus" xx;

term2str s_1';

term2str s_2';

*}

subsubsection {*build expression*}

text {*in isac's CTP-based programming language: let s_1 = Take numerator / (s_1 * s_2)*}

ML {*

(*The Main Denominator is the multiplikation of the partial fraction denominators*)

val denominator' = HOLogic.mk_binop "Groups.times_class.times" (s_1', s_2') ;

val SOME numerator = parseNEW ctxt "3::real";

val expr' = HOLogic.mk_binop "Rings.inverse_class.divide" (numerator, denominator');

term2str expr';

*}

subsubsection {*Ansatz - create partial fractions out of our expression*}

ML {*Context.theory_name thy = "Isac"(*==================================================*)*}

axiomatization where

  ansatz2: "n / (a*b) = A/a + B/(b::real)" and

  multiply_eq2: "(n / (a*b) = A/a + B/b) = (a*b*(n  / (a*b)) = a*b*(A/a + B/b))"

ML {*

(*we use our ansatz2 to rewrite our expression and get an equilation with our expression on the left and the partial fractions of it on the right side*)

val SOME (t1,_) = rewrite_ @{theory Isac} e_rew_ord e_rls false @{thm ansatz2} expr';

term2str t1; atomty t1;

val eq1 = HOLogic.mk_eq (expr', t1);

term2str eq1;

*}

ML {*

(*eliminate the demoninators by multiplying the left and the right side with the main denominator*)

val SOME (eq2,_) = rewrite_ @{theory Isac} e_rew_ord e_rls false @{thm multiply_eq2} eq1;

term2str eq2;

*}

ML {*

(*simplificatoin*)

val SOME (eq3,_) = rewrite_set_ @{theory Isac} false norm_Rational eq2;

term2str eq3; (*?A ?B not simplified*)

*}

ML {*

val SOME fract1 =

  parseNEW ctxt "(z - 1 / 2) * (z - -1 / 4) * (A / (z - 1 / 2) + B / (z - -1 / 4))"; (*A B !*)

val SOME (fract2,_) = rewrite_set_ @{theory Isac} false norm_Rational fract1;

term2str fract2 = "(A + -2 * B + 4 * A * z + 4 * B * z) / 4";

(*term2str fract2 = "A * (1 / 4 + z) + B * (-1 / 2 + z)" would be more traditional*)

*}

ML {*

val (numerator, denominator) = HOLogic.dest_eq eq3;

val eq3' = HOLogic.mk_eq (numerator, fract1); (*A B !*)

term2str eq3';

(*MANDATORY: simplify (and remove denominator) otherwise 3 = 0*)

val SOME (eq3'' ,_) = rewrite_set_ @{theory Isac} false norm_Rational eq3';

term2str eq3'';

*}

ML {*Context.theory_name thy = "Isac"(*==================================================*)*}

subsubsection {*get first koeffizient*}

ML {*

(*substitude z with the first zeropoint to get A*)

val SOME (eq4_1,_) = rewrite_terms_ @{theory Isac} e_rew_ord e_rls [s_1] eq3'';

term2str eq4_1;

val SOME (eq4_2,_) = rewrite_set_ @{theory Isac} false norm_Rational eq4_1;

term2str eq4_2;

val fmz = ["equality (3 = 3 * A / (4::real))", "solveFor A","solutions L"];

val (dI',pI',mI') =("Isac", ["univariate","equation"], ["no_met"]);

(*solve the simple linear equilation for A TODO: return eq, not list of eq*)

val (p,_,fa,nxt,_,pt) = CalcTreeTEST [(fmz, (dI',pI',mI'))];

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt;

val (p,_,fa,nxt,_,pt) = me nxt p [] pt; 

f2str fa;

*}

subsubsection {*get second koeffizient*}

ML {*thy*}

ML {*

(*substitude z with the second zeropoint to get B*)

val SOME (eq4b_1,_) = rewrite_terms_ @{theory Isac} e_rew_ord e_rls [s_2] eq3'';

term2str eq4b_1;

val SOME (eq4b_2,_) = rewrite_set_ @{theory Isac} false norm_Rational eq4b_1;

term2str eq4b_2;

*}

ML {*

(*solve the simple linear equilation for B TODO: return eq, not list of eq*)

val fmz = ["equality (3 = -3 * B / (4::real))", "solveFor B","solutions L"];

val (dI',pI',mI') =("Isac", ["univariate","equation"], ["no_met"]);

val (p,_,fb,nxt,_,pt) = CalcTreeTEST [(fmz, (dI',pI',mI'))];

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt; 

f2str fb;

*}

ML {* (*check koeffizients*)

if f2str fa = "[A = 4]" then () else error "part.fract. eq4_1";

if f2str fb = "[B = -4]" then () else error "part.fract. eq4_1";

*}

subsubsection {*substitute expression with solutions*}

ML {*

*}

ML {*thy*}

section {*Implement the Specification and the Method*}

text{*==============================================*}

subsection{*Define the Field Descriptions for the specification*}

consts

  filterExpression  :: "bool => una"

  stepResponse      :: "bool => una"

subsection{*Define the Specification*}

ML {*

store_pbt

 (prep_pbt thy "pbl_SP" [] e_pblID

 (["SignalProcessing"], [], e_rls, NONE, []));

store_pbt

 (prep_pbt thy "pbl_SP_Ztrans" [] e_pblID

 (["Z_Transform","SignalProcessing"], [], e_rls, NONE, []));

*}

ML {*thy*}

ML {*

store_pbt

 (prep_pbt thy "pbl_SP_Ztrans_inv" [] e_pblID

 (["inverse", "Z_Transform", "SignalProcessing"],

  [("#Given" ,["filterExpression X_eq"]),

   ("#Find"  ,["stepResponse n_eq"])

  ],

  append_rls "e_rls" e_rls [(*for preds in where_*)], NONE, 

  [["SignalProcessing","Z_Transform","inverse"]]));

show_ptyps();

get_pbt ["inverse","Z_Transform","SignalProcessing"];

*}

subsection {*Define Name and Signature for the Method*}

consts

  InverseZTransform :: "[bool, bool] => bool"

    ("((Script InverseZTransform (_ =))// (_))" 9)

subsection {*Setup Parent Nodes in Hierarchy of Method*}

ML {*

store_met

 (prep_met thy "met_SP" [] e_metID

 (["SignalProcessing"], [],

   {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

    crls = e_rls, nrls = e_rls}, "empty_script"));

store_met

 (prep_met thy "met_SP_Ztrans" [] e_metID

 (["SignalProcessing", "Z_Transform"], [],

   {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

    crls = e_rls, nrls = e_rls}, "empty_script"));

*}

ML {*

store_met

 (prep_met thy "met_SP_Ztrans_inv" [] e_metID

 (["SignalProcessing", "Z_Transform", "inverse"], 

  [("#Given" ,["filterExpression X_eq"]),

   ("#Find"  ,["stepResponse n_eq"])

  ],

   {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

    crls = e_rls, nrls = e_rls},

  "empty_script"

 ));

*}

ML {*

store_met

 (prep_met thy "met_SP_Ztrans_inv" [] e_metID

 (["SignalProcessing", "Z_Transform", "inverse"], 

  [("#Given" ,["filterExpression X_eq"]),

   ("#Find"  ,["stepResponse n_eq"])

  ],

   {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

    crls = e_rls, nrls = e_rls},

  "Script InverseZTransform (Xeq::bool) =" ^

  " (let X = Take Xeq;" ^

  "      X = Rewrite ruleZY False X" ^

  "  in X)"

 ));

show_mets();

get_met ["SignalProcessing","Z_Transform","inverse"];

*}

section {*Program in CTP-based language*}

text{*=================================*}

subsection {*Stepwise extend Program*}

ML {*

val str = 

"Script InverseZTransform (Xeq::bool) =" ^

" Xeq";

*}

ML {*

val str = 

"Script InverseZTransform (Xeq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

" (let X = Take Xeq;" ^

"      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

"      X' = (Rewrite_Set norm_Rational False) X'" ^ (*simplify*)

"  in X)";

(*NONE*)

"Script InverseZTransform (Xeq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

" (let X = Take Xeq;" ^

"      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

"      X' = (Rewrite_Set norm_Rational False) X';" ^ (*simplify*)

"      X' = (SubProblem (Isac',[pqFormula,degree_2,polynomial,univariate,equation], [no_met])   " ^

    "                 [BOOL e_e, REAL v_v])" ^

"  in X)";

*}

ML {*

val str = 

"Script InverseZTransform (Xeq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

" (let X = Take Xeq;" ^

"      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

"      X' = (Rewrite_Set norm_Rational False) X';" ^ (*simplify*)

"      funterm = rhs X'" ^ (*drop X'= for equation solving*)

"  in X)";

*}

ML {*

parse thy str;

val sc = ((inst_abs thy) o term_of o the o (parse thy)) str;

atomty sc;

*}

ML {*

term2str sc;

atomty sc

*}

subsection {*Store Final Version of Program for Execution*}

ML {*

store_met

 (prep_met thy "met_SP_Ztrans_inv" [] e_metID

 (["SignalProcessing", "Z_Transform", "inverse"], 

  [("#Given" ,["filterExpression X_eq"]),

   ("#Find"  ,["stepResponse n_eq"])

  ],

   {rew_ord'="tless_true", rls'= e_rls, calc = [], srls = e_rls, prls = e_rls,

    crls = e_rls, nrls = e_rls},

"Script InverseZTransform (X_eq::bool) =" ^ (*(1/z) instead of z ^^^ -1*)

" (let X = Take X_eq;" ^

"      X' = Rewrite ruleZY False X;" ^ (*z * denominator*)

"      X' = (Rewrite_Set norm_Rational False) X';" ^ (*simplify*)

"      funterm = rhs X'" ^ (*drop X'= for equation solving*)

"  in X)"

 ));

*}

subsection {*Check the Program*}

subsubsection {*Check the formalization*}

ML {*

val fmz = ["filterExpression (X  = 3 / (z - 1/4 + -1/8 * (1/(z::real))))", 

  "stepResponse (x[n::real]::bool)"];

val (dI,pI,mI) = ("Isac", ["inverse", "Z_Transform", "SignalProcessing"], 

  ["SignalProcessing","Z_Transform","inverse"]);

val ([(1, [1], "#Given", Const ("Inverse_Z_Transform.filterExpression", _),

            [Const ("HOL.eq", _) $ _ $ _]),

           (2, [1], "#Find", Const ("Inverse_Z_Transform.stepResponse", _),

            [Free ("x", _) $ _])],

          _) = prep_ori fmz thy ((#ppc o get_pbt) pI);

*}

subsubsection {*Stepwise check the program*}

ML {*

val fmz = ["filterExpression (X z = 3 / (z - 1/4 + -1/8 * (1/(z::real))))", 

  "stepResponse (x[n::real]::bool)"];

val (dI,pI,mI) = ("Isac", ["inverse", "Z_Transform", "SignalProcessing"], 

  ["SignalProcessing","Z_Transform","inverse"]);

val (p,_,fb,nxt,_,pt)  = CalcTreeTEST [(fmz, (dI,pI,mI))]; 

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

*}

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val (p,_,fb,nxt,_,pt) = me nxt p [] pt;

*}

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show_pt pt;

*}

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*}

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section {*Write Tests for Crucial Details*}

text{*===================================*}

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*}

section {*Integrate Program into Knowledge*}

ML {*

*}

end